The present invention relates generally to rotary knives and, more specifically, to an apparatus and method for monitoring and inspecting in real time the various operational characteristics of rotary knives.
Rotary knives are used in the metals industry for, among other things, slitting and edge trimming strip-metal coils. In a slitting operation, any suitable number of rotary knife pairs may be used to cut a wide, coiled, metal strip into a corresponding number of narrower strips. In edge trimming operations, two pairs of rotary knives are used to trim a metal strip of, usually, non-uniform width to a desired width.
Various operational characteristics of the rotary knives can markedly influence the quality of the strip metal edges formed by slitting or edge-trimming operations. For example, reduced sharpness and integrity, and increased wear, of a rotary knife's edge can result in poor quality edges. In addition, the respective positioning of the rotary knives within each pair (e.g., vertical and horizontal clearance), is important to strip-edge quality. Moreover, the concentricity and run-out (i.e., wobble) of individual knives can affect the quality of edge produced.
Conventionally, the setting and positioning of rotary knives, and the quality of their edges, are visually monitored and manually controlled by line operators. Through the collection of empirical data, many line operators have been able to determine "best average" knife settings for their various products. However, despite this knowledge, deteriorating knife-edge quality and incorrect knife settings frequently go undetected until significant amounts of strip metal have been cut or otherwise processed. The poor edge quality of metal strip resulting from delays in recognizing the deterioration of knife edge quality and/or knife settings or positioning can cause significant increases in reprocessing costs, reduced yields and scrap rate.